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When departing from a class C or D airfield, what is the proper VFR procedure?
Specifically, when is it legal to turn to your on-course heading?
I find that sometimes the tower will give me an instruction to "turn on course" but sometimes they don't. Are you supposed to stay on the runway heading when you do not get the instruction to turn on course, or do you just go ahead and turn after reaching some altitude?

That "on-course heading" reminded me of a good (old?) article by Don Brown here: http://www.avweb.com/news/sayagain/189197-1.html?redirected=1 . It's not exactly an answer to your question, but it's a great source to understanding why ATC assigns "runway heading" first

One thing to remember is don't be afraid to ask if you don't know. ATC is there to provide you a service and the controllers should be happy to provide you clarification.

Either C or D controllers will likely accept your requested heading, which can be given as a rough compass point, on initial contact. This contact will be after picking up the terminal info on ATIS, when you contact ground.  Your preferred direction will be passed up the chain.  A class D may tell you something like "cleared for takeoff, Northbound departure approved", in which case I would feel free to turn as soon as I deemed it safe.  In a class C scenario, the same thing could happen, but they might vector you around other traffic.  In all cases "resume own navigation" will be permission to take your heading.
If you are still on runway heading and feel you have not been given a clearance sending you where you want to go, you may contact tower or departure control, depending on whom you are with, and say something like "Tower, Diamond two-eight bravo, request heading zero six zero"  They may respond with an "approved as requested" or "heading zero six zero approved" or they may give you instructions to "fly present heading, I'll call your turn" indicating they are not ready for you to take your heading yet.
The short answer is, you can take your heading when you have been cleared to do so.  Understanding when you have been cleared is a matter of becoming familiar with standard phraseology.
Controllers I have worked with, especially at C and D airspaces have been accommodating.  Their job is to send pilots where they want to go while keeping aircraft out of each other’s way.  They have rolled along with me when I have changed my mind about landing,  I can say "I changed my mind, I'd rather depart the pattern to the south" but to be brief I'll say "Cancel landing intention, request south departure."  As airspace gets bigger and controllers are busier (which can vary by location and even time of day) brevity becomes increasingly important.  To get practice, you can find out when an particular airspace is less busy.  Controllers have been known to be chatty when traffic volume is low, and you may even be able to ask questions about preferred phraseology.

"Northbound departure approved" is the phraseology that's been going whoosh right over my head. I did not take that to be a clearance to actually make the turn. Thank you.

29R, what jurisdiction does your answer cover? Because "Northboard departure approved" is not icao-compliant, AFAIK. If I received that clearance, I'd ask the controller for clarification. I am just curious.

Speaking from experience in the Western U.S. The phraseology may be peculiar to the controllers at my neighborhood D (KPVU), but seemed to be similar to other Delta and Charlie Airspaces I've been into.  Often they will give instructions to cross a particular road before making a turn, effective for local traffic where the pilots know the geography.  I have had to tell controllers that I'm "unfamiliar" after which they will explain the features they are referencing or alter their instructions.  Charts in the U.S. have magenta flags marking named points with names for VFR reference.

At the airports I've flown out of, if I request a well-known, named departure and it's approved, I just fly the departure as they expect and they'll tell me if they want something different. For example, Reid-Hillview has something called the "Calaveras Departure" which is known to local pilots to mean turning over the Calaveras Reservoir. If they say "Calaveras Departure approved" before takeoff, you just fly the departure and typically they just tell you when you can change frequencies.


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Does anyone know of sources for ATA 206?
I have been seeing references to 206 ATA recently. However, it appears to be so new that very little Google indexed information is available.
Has anyone dealt with this particular  ATA chapter, and if so are there any publicly available resources?

Please note: I am not talking about USS Pinola (ATA-206).

Are you asking about USS Pinola (ATA-206)?

Alas, no. That one does actually show up on web searches. I am asking about the  chapter in Airlines for America (formerly  Air Transport Association) spec 100 (or whichever actually has chapter 206).

Can you provide any more information about this ATA 206? Where is it referenced? What is the subject?

Wikipedia claims that the ATA-100 scheme was superceded fifteen years ago. If true, this makes it difficult to imagine that Chapter 206 could be very new. From what I can tell, the ATA-100 numbering system stopped at around 115, so 206 seems a leap forward. Maybe it's some sort of proprietary extension of the numbering scheme?

ATA 100 has been superseded by ATA iSpec 2200 (which is in fact a result of the merge of ATA 100 and ATA 2100). Neither in ATA 100 nor in ATA 2200 there's something such as a chapter 206.

Airlines for America (formerly known as Air Transport Association of America (ATA)) maintains a website for their publications and subscriptions. You can access all/several of their specification documents.
Spec 100 (Manufacturers' Technical Data) can be downloaded from this page, by just paying an exorbitant a minimal fee of $650.
I am not sure which spec contains Chapter 206.

I guess you can keep paying the very reasonable fees until you find the spec you are looking for.

That got a chuckle

@user7632 If this answers your question, please mark it as answer.

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text:
Why don't airlines have in-flight video recordings like buses do?
That way we could study plane crashes more closely, or terrorist hijackings, or resolve passenger disputes. Even buses in Ecuador have video cameras.(WARNING: shocking video)

That YouTube link is shocking and disturbing !

I feel it imperative that pilots be given, in flight, a view (or views) of the engines and control surfaces so that failures may be quickly and accurately identified.

Many airlines do in fact have inflight camera feeds for Cabin surveillance so I do not think the question is relevant to most major airlines anymore.
For a specific example, Emirates Airline employs the Cabin Video Monitoring Systems (CVMS) across its fleet of Airbus A380 aircraft. These Cabin cameras can be accessed by Cockpit crew through the System Display or the Cabin crew through the FAP (Flight Attendant Panel) and for any abnormal situation such as a hijacking/hostage situation on ground, the CVMS can be accessed on a laptop via the GSP (Ground Service Panel). Additionally, as mentioned above, they have landscape cameras installed for an external video feed but that is more of a feature for passengers.
The advantages of a CVMS in a hijacking/hostage situation such as positioning, identity, body language and weapons of the hijackers plus general operational advantages such as issues during boarding/offloading and other emergency situations such as an evacuation are great and not to be discounted.

It's not clear from your post whether video from the existing cameras is recorded (which is part of the question).

Regarding cabin cameras, there's not much of a need for them. Busses typically don't have flight attendants. In-flight disputes are typically handled well and quickly by the cabin crew on an airliner. Also, theft or assault would have dozens to hundreds of eyewitnesses and no route of escape for the perpetrator, unlike on a bus (which is probably why such incidents are almost completely unheard of on airliners.) In the case of a terrorist hijacking, having video wouldn't really help much. It's usually pretty obvious when an airliner has been hijacked, but there's not a lot that people on the ground can do about it, aside from the possibility of shooting it down if it appears to be threatening a 9/11-style attack.
Regarding exterior cameras, these are actually starting to appear on some airliners now. Newer airliners like the 777-300ER and the A380, for instance, have them, though I don't think they actually record the video. Even if they did, it seems unlikely that they'd provide any useful information beyond what the FDR data and accident scene examination had already revealed (i.e. they'd basically just show that the plane ran into the ground, which would already be known by the time you found the video.)
Regarding cockpit video recording, there is an answer here that addresses it. There have been some suggestions for this to be added over the years, but pilots tend to be against it and the additional information it would provide would likely not be particularly useful in most instances, given that we already have a recording of all of the conversations up to the time limit of the recorder as well as the FDR data.

Note that cockpit voice recorders don't give you a recording of all conversation: they give you a recording of all conversation in the (typically, as I recall) two hours before they were switched off. So, for example, the CVR from MH370 is ever found, it will probably be no use, since the plane flew on for hours after it changed route, so the critical conversations will have been overwritten multiple times.

@DavidRicherby Good point. I meant all of the conversations taking place while they're recording (i.e. radio calls as well as conversation between the crew members,) but you're right that the time duration is limited. Normally the last two hours would be plenty to capture everything relevant to an accident, but MH370 is indeed a notable example where it likely wouldn't be. These days, one would think it would be trivial to remove that duration limit, though a new design would have to be recertified.

CVMS (Cabin Video Monitoring Systems) can definitely help in a hijack situation on ground to aid authorities in establishing various attributes related to the hijacking situation. This information may include 1) Identities 2) Positions 3) Weapons 4) Body Language 5) Others. There's a reason why many airlines employ such systems.

@Kamran OTOH, every system has to have a fuse, and the hijackers may easily know how to switch it off.

@yo' Of course there are lot of components that can be damaged by any hijackers but that goes for any security measure, nothing is 100% secure. The balance of probability suggests that it will be very difficult for anyone to disable this particular system (Or others configured like it). The power for the CVMS (Cabin Video Monitoring System) can also be through the GSP when the laptop is connected for external viewing. Additionally, the access to the CB's (Circuit Breakers) would be through the Avionics Bay which is accessible from the Cockpit, Externally or the Forward Cargo Compartment.

Note that cameras are already installed in some aircraft; but I believe this is an operator option and not standard equipment.
For example, from this incident report of a 737-800 PDF:

The captain stated that he could see on the cabin observation camera
  screen in the cockpit that a CCM was wearing personal breathing
  equipment (PBE). The captain switched off the IFE. This action also
  switched off the camera since the IFE and the camera are on the same
  electrical bus.

You will see them very soon. Actually, I have already made the software for that :) and we will be delivering to few of the Airlines very soon as I work on those systems where we will have the DVR (Digital Video Recorder) and and a live streaming panel. This recording is only manually controlled just by push of a button by pilot or crew. You will see them in B787s. There are few in A350 also for few airlines.

A lot of airlines already use Cabin Video Monitoring Systems and already have live display on the Flight Attendant Panels. The software(s) already exist for such systems are in use for various aircraft belonging to various airlines.

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Is an aeroplane's design only functional?
Many parts of a car are not obligatory. They are attached or formed to make the car look better.
Are aeroplanes(especially airliners) only designed for function or are there any parts that are purely for aestethical reasons (On the outside of course)?

Which planes? GA, gliders, airliners, military? Indeed GA planes include some aesthetically aspects. Military, not sure.

I am interested in every type of plane.

This is quite broad, a single answer may not cover marketing and technical aspect for all kinds of buyers. For airliners: Why is there really only one basic design for passenger airplanes? Now there is a big discussion about nose differences between Airbus and Boeing: Is the shape choice technical or aesthetic? Same for tail design at Mooney.

@mins Ok, I limited it to Airliners.

I don't know about now, but nobody can tell me there wasn't an element of aesthetics in the design of the Spitfire.

The question is very broad so I gave a quick overview, please comment and I will elaborate further by editing my answer.
Jet liners are purely designed for function, they are all about transporting x amount of passengers for the lowest cost per mile. That trend started after the oil crisis. The Boeing 747 was originally developed as a cargo airplane such that when we would by flying supersonic they could be converted from pax to cargo. This all went south and supersonic flying was not the future anymore. The 777 program was one of the first jet fully optimized to fit as many pax in it as possible, just look at two seat plans, one for the 747 and one for the 777

Boeing 747

Boeing 777
As can be clearly seen by the picture above is that the 777 has far less space left with no seats thus fitting in more pax per square meter.
In the private jet world design is still functional but there is more freedom to waste some fuel on unnecessary bits if this makes your aircraft stand out. This would result in aircraft like the:
Beachcraft Starship

Piaggio Avanti

They both feature a more complex design involving a Canard configuration which has advantages but also major drawbacks
Moving over to private jets a similar trend as in the civilian market can be seen where designs are more alike due to the simple fact that jets are expensive and you will most probably only see the inside as it is parked in a hangar anyways and you can't drive it over the boulevard so everyone can see it

Honda Jet, interesting looking aircraft but still mostly functional as mounting the engines aft reduces the noise inside the cabin, high mounted engines allows for unpaved runways and reduces the risk of FOD from the runway.

I can add that currently even if an aircraft is designed to accomodate lounges or maybe gym (A380 was originally presented with this kind of features due to large space), airlines quite always prefer to fit them with seats and not this kind of amenities, to maximise profit


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Do modern Terrain awareness and warning system (TAWS) have blind spots?
Do Terrain awareness and warning system (TAWS) have blind spots when the helicopter is in unknown territory with unpredicted terrain or the TAWS systems coming nowadays have each and every terrain on earth?

Almost all EMS, Law-enforcement and SAR helicopters based in, say, Los Angeles. are unlikely ever to need to fly in, say, Novosibirsk at very short notice. Presumably their mapping data can be replaced when redeployed.

Some TAWS systems, such as the ones on military aircraft, are based at least partially on terrain-following radar; these systems would be able to operate globally with minimal need to update a topological database.

This answer is only applicable to civil airline type operations. Military systems do have significantly different requirements which I cannot address.
Quick Answer:
No, they don't have "blind spots" in the sense of areas with no data available.
A TAWS system works differently:
In the airline I've worked for, I was "exposed" to Honeywell Mark V EGPWS systems, but I assume that other systems are similar. These systems have a world-wide terrain database. That database and the algorithms take a normal terrain clearance into account as well as the performance of the aircraft.
"Holes" or "Corridors" are "cut" into this "terrain clearance carpet" to avoid nuisance warnings when an aircraft needs to descent below the normal margins. I.e. during landing and takeoff.
So, these aircraft can safely operate world-wide unless there are new mountains growing (which actually happens with volcanos) or large man-made obstacles are built.
As with all databases on board of an aircraft, they are updated on a regular basis.
Except for this link, I was not able to find an awful lot of information from manufacturers.


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Can a Boeing 747 take off fully loaded on 3 engines?
Recently a Boeing 747 aborted a take off while still on the ground due to the failure of one engine.
Can a Boeing 747 take off fully loaded on 3 engines?

This is a question that cannot be answered without further information. A short form answer is that if the engine failure occurs before the speed typically labeled as V1, the takeoff must be aborted as the probability of getting off the ground before the end of the runway is reached is small. If the failure occurs after the V1 speed, the takeoff should be continued and will normally succeed. If there is an attempt to abort after V1, the aircraft will typically be unable to stop before the end of the runway. The V1 speed varies by aircraft weight, altitude, and temperature.

@Terry Didn't you just answer the question? "If A then X; else Y" is a perfectly valid answer.

@DavidRicherby Yeah, I guess you're right, but I am often obsessed with more detail than I have energy to properly compose, so I just comment. I'm quite happy to let those that have that energy get the rep points with a detailed answer.

The short answer as detailed to some degree in previous answers and comments is that a 747 can takeoff if the engine fails after the V1 speed is reached but not if the failure occurs before reaching V1. Unfortunately, in my opinion, the owner of one of the answers has deleted his answer, which while perhaps imperfect did provide useful information, and perhaps as important will remove the comments.
It's best to understand the V1 speed within the context of a balanced field takeoff. See this Wikipedia article for a full explanation. The first two paragraphs are:

A balanced field takeoff is a condition where the accelerate-stop distance required (ASDR) is equal to the takeoff distance required (TODR) for the aircraft weight, engine thrust, aircraft configuration and runway condition.1 For a given aircraft weight, engine thrust, aircraft configuration, and runway condition, the shortest runway length that complies with safety regulations is the balanced field length.
The rejected takeoff initial actions speed V1, or critical engine-failure recognition speed (Vcef),is the fastest speed at which the pilot must take the first actions to reject the takeoff (RTO). At speeds below V1 the aircraft may be brought to a halt before the end of the runway. At V1 the pilot must continue the takeoff even if an emergency is recognized.

Let's translate this into a practical situation using a 747-200 with old steam gauges. Prior to engine start five plastic bugs would be positioned around the rim of the airspeed indicator: the first at V1, the second at VR, the third at V2, and the last two at speeds not relevant to our discussion. We're rushing down the runway at takeoff power and all goes well. When we reach V1, the PNF says "V1" and the PF takes his hand off the thrust levers (he had them there in case of an abort). When we reach VR, the PNF says "rotate" and the PF brings the yoke back briskly but smoothly to a pre-determined nose attitude (usually 12 or 13 degrees). When the landing gear is off the runway, you'll hear the gear down lock retract unlocking the gear up lever. When the PNF sees a positive climb rate on the vertical speed, he'll say "positive rate", the PF will call "gear up", the PNF will move the gear lever to up. When the airplane reaches V2 the PNF will say "V2".
The important thing to remember here is that if there had been an engine failure after V1, the only difference would have been that the first person to know which engine had failed would have called "engine failure #1" say. On the old 3-crew airplanes, that would usually be the f.e. Even if the engine was burning, no action would be taken until after V2, and probably not until after you had a clean airplane.
Just as a matter of information, here are some V speeds for a 747-200 with P&W JT9D-7Q engines for a Flaps 10 takeoff at 840,000 lbs:

V1 168 kts
VR 181 kts
V2 189 kts

Now for an abort. An abort below 80 kts is no big deal. Between there and 100 kts gets more interesting. Above 100 kts it is not to be taken lightly, and an abort at say, 150 kts, is a bonafide emergency. A friend of mine had to do one of those, and he blew all of the 16 tires that had brakes. In my view, if an engine failure occurs within a few knots either way of V1, you're better off flying.
To quote from an accident report in which I was involved in the investigation:

The bang and the loss of power occurred around V1 speed. Two seconds after the bang, all four engines were brought back to idle, and braking action was initiated. The thrust reversers were not deployed.
The aircraft came to a stop 300 m after the end of runway 20, above a railroad embankment. The aircraft was severely damaged; it broke in three parts.

Aw, shucks -- I wouldn't have the foggiest clue if the Belgian accident investigators keep their investigation dockets online.  I was looking forward to seeing your name in the docket :)

@UnrecognizedFallingObject When a U.S. aircraft crashes, the FAA goes over everything, understandably so. In this instance an FAA investigator looked at the weight and balance report. When he added up the weights of the individual ULDs, his answer differed from report's total by one pound. Since I wrote the W&B software that was used, it fell to me to explain how that could be. I had to produce a paper that showed why, if you entered the ULDs in kilograms, which the program then had to convert to lbs, it is the nature of floating-point arithmetic that this can happen and is correct.

ah! :)  Understandable, then.

Phew!! I thought you were pilot on that flight.

For another explanation of BFL, see my answer here on Aviation.SE.

Somehow, I missed this A when it was first posted. It's great to see that it comes with another great @Terry story! After looking at those accident pics, I'd hope that plane was a write-off, that's a bit of a mess...

Wow... the angle of that slide.

You would have to define "fully loaded" but in general, yes you can take on three engines. It is dangerous to fly on three engines because the thrust is imbalanced. Therefore, it is highly preferable to abort, if that is an option.

Seems Boeing can even commence takeoff run with three engines: http://www.avherald.com/h?article=492675e0&opt=0 What do regulations say about this?

Yeah. 3 engines and a full load of 1000 lb bombs apparently. Scary.

@curious_cat -- I suspect the airplane was unloaded for the return flight to Minsk -- I doubt you can do a 3 engine ferry with cargo.

@UnrecognizedFallingObject True. My bad. I meant to say scary letting an off practice captain land a plane full of bombs and who lands so badly.


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Do multiple go-arounds on the same flight happen in commercial aviation?
I know that go-arounds are pretty rare: somewhere around 2 per 1000 approaches. In large commercial aircraft the rate is probably even lower due to crew quality, instrumentation, conservative decisions etc.
But are there instances of multiple go-arounds having to be initiated by a flight crew on one flight? I'm just curious to hear of any such stories. Two GAs? Three GAs?
I suppose if the reason is Weather related or equipment related the chance of a multiple go around might exist?
A related question is after how many weather related go-arounds would the crew decide to divert to the alternate. Either by rule, company procedure or plain heuristics.
P.S. Let's restrict this to non-training flights by scheduled airlines.

If weather deteriorates below published minimums during the approach you are allowed to continue, but you would not be legal to perform subsequent approaches to the same minimum having never broken out.

@RhinoDriver, if the problem is wind rather than visibility it is quite possible. The wind can change rapidly and gusts are rather random, so when the first approach is foiled by too strong wind gust, the crew may try one or two more times before deciding to divert.

I believe I've seen some incident on AvHerald where plane went around, diverted and went around at least once at the diversion field too. I don't remember what the incident was to find it now.

Just this week there was a flight that had 6 go-arounds http://avherald.com/h?article=48b217ed&opt=0

@JanHudec sure, I just wanted to clarify that multiple go arounds for minimums generally won't happen.

If the pilots here had decided to try only 2 times and not 3 times, the lifes would have been saved: https://en.wikipedia.org/wiki/Manx2_Flight_7100 (Now I don't want to be iffy, just to refer to this plane disaster where multiple approaches was likely an important factor.)

Just a note, there's never an apostrophe involved in any type of plural.  Signed, your copyediting pal  :)

None of four airlines I worked for (two commuters, two Part 121) had specific guidance as to the max number of go-arounds. However, as mentioned in the other answers, 2 or 3 was believed to be a good rule.
The only time I did multiple go-arounds, all missed approaches, was trying to get into Pullman, WA during a snowstorm in the late 1980s in an SA-227 Metroliner. I tried the VOR approach 3 times. Each time when we got down to the MDA, we did not have the forward visibility to descend further. Each of the 3 times the station personnel saw us pass over, and each time passengers looking out the windows saw the runway below us when we were overhead. That, of course, resulted in our being criticized when we arrived at our alternate by some passengers for not having landed at Pullman. I had explained en route to the alternate the problem with forward visibility, but when you've disrupted people's travel plans, they don't want to listen.
I briefly considered the feasibility, when we were over the runway, of entering a tight left turn to see if I could keep the runway in sight, but I rejected that. And, yes, I considered descending below the MDA before catching sight of the runway. That would have been doable as I was very familiar with the airport and knew that the gently rolling fields around the airport topped out well below the MDA.
The problem was that with all the snow on the ground and the snow in the air, we couldn't determine our altitude above the ground visually until we were actually over the runway. The fields around the airport had no trees, they were wheat fields in season. Even if I had chosen to bust the MDA, I still would have been too high for any kind of a normal landing when I caught sight of the runway end. If getting down was an emergency, we could have done it. It wasn't technically legal, but you could go into beta with the props and really drop out of the sky, then as you flared come out of beta. But it wasn't an emergency, so we went to our alternate, which was actually our next stop anyway, so all of the passengers weren't unhappy.
The advantage of multiple approaches is that conditions might get better while you're doing them, and you can get in. The disadvantage is that the nervous energy you're expending is telling.
Our SA-227s had no-autopilots, no radar altimeters, and, of course, no GPS. I imagine that these days that airport has one or more GPS approaches that would make landing in those conditions a piece of cake.

Thanks Terry! Would love your comments on the 7 Go Arounds recent incident posted on this thread.http://avherald.com/h?article=48b217ed&opt=0

@curious_cat Discussions live in [chat], not in the comments sections of answers.

Thanks Terry, always a pleasure to read your contributions to this site.

Sounds like a case of "Thank God such a sensible pilot was in charge!"

Multiple go-arounds are pretty rare, as already stated. However they do happen.
I think this takes the cake in go arounds.
In this case, the pilots of Boeing 737-800 (VT-JFA), flight 9W 555 from Doha to Kochi tried to land (and failed) for six times in two different airports (Kochi and Thiruvananthapuram) before finally landing in Thiruvananthapuram on the seventh attempt.
According to reports

Despite the pilot having listed Bengaluru airport as the alternate airport to land, he instead chose to head for Thiruvanathapuram where he again made a “go-around” thrice over that airport which was also facing bad weather. Finally, left with not much of fuel, the pilot declared a fuel emergency and landed the aircraft at the airport there.

The flight was diverted from Kochi (after three landing attempts) due to bad weather. Reportedly, the flight has a reserve fuel of only 270kg (of the minimum requirement of 1500kg) at that point. Both the pilots ended up suspend by the regulatory authorities.

http://avherald.com/h?article=48b217ed&opt=0 <-- better link on this incident, and yes, I suspect this take the cake on go-arounds!

@UnrecognizedFallingObject Wow. Just wow. That's pretty crazy. Is that the equivalent of a plane flying on fumes? It says they had 250 kg fuel left on landing. This could have ended a lot worse.

@curious-cat Yeah, it was pretty close to being the next Avianca 52.  Waaaay too close, if you ask me.  They should have realized "hey, this choice of alternate sucks, lets try a different 'drome" when they had to do the first go-around at their chosen alternate.

What did the investigation said ?

@Antzi  The incident happened on August 18th 2015; the investigation is almost certainly ongoing.

Why suspend the pilots? Surely the airline was the catalyst to all that?

Yes an aircraft occasionally perform multiple go-arounds. Sometimes weather(windshear the most common culprit) to ATC trying to squeeze out another departure or getting too close to the aircraft in front, necessitating a go around. General rule for multiple approaches, would be 2 or 3 before diverting to an alternate. A problem if you try to shoot too many approaches, is you start getting anxious and have a "get there-its" where you get so focused on getting on the ground you end up causing a major accident.

I once had a flight in region NSW (Australia) in bad weather. We had 3 go arounds at destination, then diverted to another, 2 go arounds then diverted again, 2 more go arounds and eventually went back to original airport and landed first attempt. We were very late and they had to get another plane to take us on to sydney... long time ago though

which kind of flight was it? scheduled commercial?

I flew American Airlines to Narita Japan on February 19, 2017.
As we approached Narita on February 20, we were informed by the pilot to expect a bumpy landing.
Our scheduled arrival was for 16:50.
After 4 failed attempts at Narita, the pilot diverted the flight for Haneda where he failed the 5th landing.  Finally, on the 6th try, he was able to get the plane on the ground safely at 19:00.
Needless to say, that was a relief.

Welcome and thanks for the personal experience! Can you provide the flight number? I'm sure there are many nerds, erm, aficionados here who would love to look at the details.

I live right next to BOS Logan Airport.  On August 19, 2017, flight FX3719/FDX3719 attempting to land in fog, tried to land on Runway 15R twice.  As soon as he was about 100 ft, the fog closed in to zero visibility and that's when he executed the go-around twice.  I saved an image of the flightpath through a website I won't name here.  After the double go-around he then landed without incident on runway 4R.  This all took place just after 7:00 PM EST with a recorded landing time of 7:32 PM EST. I see occasional go-around's at Logan, but this was the first double one I've seen.


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How close can separation be during a landing clearance?
How close can separation between two aircraft be during landing? during visual landing clearance?
Specifically, I refer to this Aviation Herald Report where:

When the Boeing 777-300 was about 2.1nm before touch down a BAe Avro
  began its takeoff run on runway 08R. The Boeing 777 was subsequently
  cleared to land on runway 08R, winds from 130 degrees at 7 knots.
When the Boeing 777-300 crossed the runway threshold, the Jumbolino
  was climbing out still short of the runway end.

(Source: www.avherald.com - Singapore B773 at Munich on Nov 3rd 2011, runway excursion)
Is it typical for two aircraft to be so close during landing? i.e. Essentially both landing & departing aircraft are simultaneously overflying the same runway but at opposite ends.
How much closer would cause the landing aircraft to abort? Would one proceed with landing even if when one crossed the threshold the other craft was just rotating?
There's other things that went wrong in that incident,  but I'm only asking about the close separation in the landing clearance visual clearance aspect.
PS. I've edited the question to remove a confusing misunderstanding. It was apparently not a visual clearance.

Which jurisdiction was this in? Different jurisdiction will have different separation minima during approach phases and also when landing clearances are issued.

@SentryRaven This was German jurisdiction.

What gives you the impression that the B773 was doing a visual approach? The airport was under CAT I operations.

I would love to answer the question, but you are asking about a visual landing clearance and the avherald article you reference and the incident itself were not conducted under VMC and under CAT I procedures. Many things went wrong with this incident, but the landing clearance part for this incident can be answered. It just wasn't a visual approach...

@SentryRaven My bad. Someone else in a comment on another SE Aviation Question mentioned that this had happened in a "Visual Environment". I misunderstood that to be a Visual Clearance. http://aviation.stackexchange.com/questions/24231/unusual-pilot-requests-to-atc-during-approach-landing/24233?noredirect=1#comment56506_24233 I've edited this question to remove the wrong information.

I guess my answer will then be sufficiently answer your question. Let me know if I need to elaborate on any part...

@SentryRaven Thanks very much. Yes, your answer addresses my question very well. One additional thing you could clarify perhaps is how these separations change, if any, for other modes of operation e.g. CAT II A / B or CAT III or Visual. What governing rules exist for those cases and how close a Landing Clearance may be allowed.

During actual CATII / CAT III operations, the separation on the ILS can be increased to prevent interference. There will also be another separation minimum between departing and arriving aircraft, so not to cause interference by departing aircraft flying over the localizer antennae, as in the case in Munich. You also have different ILS protection areas. During visual approaches, you can also apply radar separation or visual separation. Many Many Many factors and options.

According to the avherald article, the airport was operating below visual minima, thus no visual approach would have been possible. Unfortuntely, the ATC communication transcript is not available, so we will will not know whether the CAT III AutoLand approach by the B773 was communicated to ATC, which would not allow the Avro to enter the runway protected area during the B773's approach or whether this was a decision by the B773 crew only.
Since the airport was operating under CAT I procedures, the B773 is likely to have been cleared for a CAT I ILS approach. The Avro will have been cleared for departure before the B773 was cleared to land, ATC has most likely used a non-withheld landing clearance.

321.5 Landing clearance need not be withheld until prescribed separation exists if there is reasonable assurance that the appropriate separation will exist when the aircraft crosses the runway threshold. However, do not clear an aircraft to land before a preceding landing aircraft has crossed the runway threshold.

The runway is considered no longer occupied if the preceding departing aircraft has reached Vr and has rotated, although still being over the runway. If ATC can be reasonably sure that this will be the case when the landing aircraft crosses the threshold, the landing clearance can be issued.
The BFU bulletin reads:

The B777 crossed the runway threshold of 08R at 12:09:09 in 40ft. Six seconds later, the BAe Avro crossed the opposite runway threshold at approx. 380ft.

(Source: BFU Bulletin NOV 2011 - Translation: Own Work)
Is it typical for aircraft to be so close during approach and departure? Yes, aircraft can be close during these phases, depending on procedures in use and meteorological conditions. Aircraft can be asked to maintain visual separation to preceding traffic in VMC, however without the full transcript of the ATC communication, this will not be answerable in regards to your scenario in Munich.


text:
What is the difference between the airspace's classes (for non-pilots)?
When I'm reading about aviation, it's very common to see references to Class B or Class C airspace and airports.
What are the different classes and what are the differences between them?

Although Lnafziger's answer is correct, I'd like to elaborate on the purpose of the airspace classes.

Class A: This airspace is intended for high-speed, point to point travel.  That is why pilots flying in Class A must be instrument rated and in contact with air traffic control (ATC); aircraft above 18,000 feet are likely to travel quickly and may not have time to avoid each other visually.  This is the upper layer of the airspace system.*
Class B: This airspace is intended for large airports with lots of jet traffic.  The large number and size of aircraft require space for ATC to get them efficiently in and out of the airports.  Approach control services are provided.  As a result, class B areas are physically large.  It is possible for small aircraft flying under visual flight rules to operate here with explict ATC permission, though permission to enter may be denied during periods of high traffic.  Small piston-powered aircraft land at Class B airports infrequently, typically due to high landing fees and fuel prices.
Class C: Smaller airports with a mix of piston-powered aircraft and jets.  Most Class C airports are home to flight schools and small aircraft hangars as well as scheduled service by airlines.  While still busy, Class C airports have less traffic than Class B, so ATC doesn't need as much space to keep them organized.  Like Class B, approach control services are provided.  Pilots are only required to establish two-way communication to enter the airspace.
Class D: The smallest airspace type for tower-controlled airports, traffic primarily consists of general aviation aircraft.  Often these airports handle cargo, business jets, charter service, maintenance or assembly facilities, etc. as well as private aircraft and flight schools.  They also host firefighting operations, airshows, or anything else that needs facilities but would interfere with normal traffic if put at a larger airport.  Although Class D airports are small, some are very busy; others handle only a few flights an hour.  Approach control services are only provided if the airport is near Class B or C airspace.
Class E: This is the lowest level of "controlled airspace."  "Controlled" doesn't mean you have to talk to ATC, but that ATC services are available (within the capabilities of radar and radio equipment).  This is general-purpose airspace.  Aircraft flying under visual flight rules can fly more-or-less whatever they want (weather permitting), and instrument flight rules traffic operate under positive control by ATC.  There are regulations in this airspace, but they aren't onerous, and they're designed to accommodate the wide variety of aircraft and activities that are found here.  Some small airports have Class E airspace surrounding them at the ground.  Although Class E is a single class of airspace, there are tighter regulations above 10,000 feet, where there are no speed restrictions (other than the prohibition on supersonic flight over land), compared to at lower altitudes where speeds are limited to 250 knots.
Class F: See What is Class F airspace, and why is it not used in the US?
Class G: This is found near the ground everywhere except controlled airspace around airports, and occasionally at higher altitudes in remote areas (Alaska or the Rockies, usually), but never above 14,500 feet.  Most untowered airports have Class G airspace surrounding them.  This is "uncontrolled" airspace, so there is no ATC service available at all.  Radio and radar work better the higher you go, so at low altitudes you just can't expect good results.  Class G serves as a notice that ATC services are unavailable, typically due to a lack of radar coverage.  In remote areas, the same problems occur at higher altitudes (radar won't see you if you go behind a mountain, and sometimes you're just too far) so Class G is found there as well.  Most of the time, the only reason anybody goes into Class G airspace is because they're taking off or landing at an uncontrolled airport, or transiting certain areas that lack radar coverage.
Other: There are many kinds of special-use airspace, all of which serve as keep-out signs of varying levels from "please be considerate" up to "will shoot on sight."  In the US, these don't really interact with airspace classification.

* Technically, airspace above 60,000 feet is Class E, but nobody goes up there except scientific and spy/military flights.

The decision to make an airport class B, C, or D is based on the number of operations, not the size it speed of the airplanes.  It usually ends up that way, but it isn't the reason why. Also, I've flown into Class B airspace lots of times in small airplanes and never been denied like you say is likely. In fact, they have always been very accommodating and if IFR, they can't deny any properly equipped aircraft from entering Class B. Again, in Class B it isn't about the speed, it's about knowing where all aircraft are and keeping them separated.

You don't need permission to enter class C; it's only necessary to have established contact with ATC. Of course, if ATC doesn't want you to enter, they just pretend they didn't hear your call sign.

Or they say "Remain outside the class C".  I've actually heard - only once - a controller direct an aircraft to turn around and leave the class C and not come back that day.  (the airspace was extremely busy and the pilot was not only talking.....very.....slowly... but was well known to get clearances wrong)

The descriptions in this answer are correct, but the editorial comments are way off base. For example, anyone can fly in Class B airspace and permission is routinely given to small planes to transition the airspace and even land at the big airport. Likewise, I wouldn’t categorize 'Class E as mostly Cessna’s puttering around'. The majority of piston aircraft fly spend most of their time in Class E airspace. You’ll find everything from local sightseeing flights to twin engine charters in this airspace. As well as the jets trnsitioning to Class A airspace.

The short version, for non-aviation people is as follows:

Class A: All Airspace above 18,000 ft. Anybody flying here must receive a clearance from, be talking to, and be controlled by ATC.
Class B: Airspace within approximately 30 miles and 10,000 feet of the ground around the busiest airports in the US. Again, anybody flying here must receive a clearance from, be taking to, and be controlled by ATC.
Class C: Airspace within approximately 10 miles and 4,000 feet of airports that are less busy than Class B airports. The equipment requirements are less restrictive to fly in this airspace and pilots must be talking to ATC.
Class D: The airspace around the least busy airports that still require an ATC control tower. It is approximately 4 miles and 2,500 feet of airspace and they usually don't have radar so just coordinate with airplanes over the radio and by sighting them visually. Pilots must also talk to ATC before entering their airspace.
Class E: Airspace that does not require aircraft to talk to or be under the control of ATC unless the weather is worse than certain specified criteria.  Aircraft avoid each other by looking out the window, and while this is true in the other airspace above, it is particularly important here (and in Class G) since many aircraft don't talk to ATC. There is an exception for airports in Class E that have a control tower; pilots landing at these airports must contact the tower before entering the airport's airspace.
Class F: Not used in the United States
Class G: Uncontrolled airspace that aircraft do not have to talk to ATC at all, except that are some airports in Class G that have a control tower; pilots landing at these airports must contact the tower before entering their airspace.

So could I define Class G airspace as any airspace that is below 18,000 feet and not near any airports with towers, or near the smallest airports with towers while the weather is good?

@AbbyT.Miller Nope, the official definition is "Class G airspace (uncontrolled) is that portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.".  Class E is automatic above 14,500 ft., and in the US most class G is below 1,200 or 800 ft. above the ground, depending on the location.

Your Class B and Class C definitions don't really mention that its an upside-down wedding-cake shape, and that uncontrolled GA traffic can be well inside the 30-mile radius, but below the class B space.

@abelenky This is for non-aviation people and I said "approximately".  No need to get bogged down with so many details for the purposes of this question.  :)

Abby, The airspace (away from airports) below 1,200' is usually Class G. There are also large areas of Class G airspace in the mountains of the Western US. The reason it is uncontrolled airspace is because radar coverage is not available.

@JScarry airports can be in Class G and also in class E http://www.law.cornell.edu/cfr/text/14/91.126

The answers given are correct for the USA. If you're in one of the other 199 (or so) countries, it's more likely that something closer to the original ICAO (International Civil Aviation Organisation) definition of airspace applies.
They specify (a) what sort of traffic is allowed, and (b) who is responsible for avoiding other traffic, namely ATC (when separation is provided) or the pilot.
Below, IFR refers to Instrument Flight Rules, while VFR refers to Visual Flight Rules.

Class A: IFR only. All aircraft are subject to ATC clearance. All flights are separated from each other by ATC.
Class B: IFR or VFR. All aircraft are subject to ATC clearance. All flights are separated from each other by ATC.
Class C: IFR or VFR. All aircraft are subject to ATC clearance. IFR flights are separated from each other and from VFR, but VFR flights are not separated from each other.
Class D: IFR or VFR. All flights are subject to ATC clearance. IFR flights are separated from each other, and are given traffic information in respect of VFR flights.
Class E: IFR or VFR. IFR flights are subject to ATC clearance. IFR flights are separated from each other, and are given traffic information in respect of VFR flights.
Class F: IFR or VFR (no SVFR). ATC separation will be provided, so far as practical, to aircraft operating under IFR.
Class G: IFR or VFR (no SVFR). ATC separation is not provided. Traffic Information may be given as far as is practical in respect of other flights.

Individual countries can (unfortunately...) deviate quite substantially from these airspace classes, and/or impose further structure on top of them.
Frequently, certain air space classes will have specific speed limits, equipment requirements, or minimum visibility requirements for VFR traffic.

Hi Fab, welcome to the site!  If you look under the question, you will see that this question is tagged faa-regulations, so is specifically asking about the USA and not ICAO or the other 199 countries.  Because there are so many different possible answers to a question like this, we use the tags to limit the scope of an individual question. Your answer would be great for a similar question tagged icao-recommendations, and I would suggest adding an appropriate question along with your answer since you already went through the trouble to write it up! See [ask] and [answer] for details.

Hi Lnafziger, thanks for your welcome and note. Good point! The tags are easy to overlook though - maybe one would want to delimit the scope in the question, as well.

Sometimes people do in their questions, but it just takes one comment to a new user and they know how it works. I tend not to on my own questions because it is redundant, but that's just me.  :)

This question is quite broad, as airspace classes are used in varying ways by different jurisdictions. The only near-constant is what the airspace classes mean in terms of the services Air Traffic Control must provide and the conditions under which planes may use the space.
First, you must understand four basic modes of aircraft operation:

Visual Flight Rules (VFR) - Pilots fly the plane primarily by looking outside the cockpit, using the horizon to know how their aircraft is oriented, landmarks to navigate, and visual contact with other planes and airborne objects to safely "separate" his aircraft and avoid collisions (a mentality known as "see and avoid" which is required of all pilots when it is possible). This is the simplest mode of operation and the first that pilots learn, but requires good weather, especially good visibility distance (3 miles or better) and a high cloud ceiling (1,000 feet or higher). The minimal conditions required for VFR are known as "visual meteorological conditions" or VMC.
Instrument Flight Rules - Pilots fly the plane using primarily instruments inside the cockpit for orientation and navigation of the aircraft, while Air Traffic Control (ATC) issues directions to aircraft regarding course and to maintain separation between one plane and another and direct planes onto the correct course, especially for landings. This requires pilots to receive special training on the instruments they'll use and in radio procedures, and allows flight in any weather that doesn't meet the minimum criteria for VMC but still allows the flight of aircraft (fog, low clouds, light rain, dust storms), which is known as "instrument meteorological conditions" or IMC.
Special Visual Flight Rules (SVFR) - An exceptional case in which pilots are allowed to fly under VFR within controlled airspace in weather conditions marginally worse than the minimums in which VFR is normally allowed. ATC is required to track the aircraft and provide separation even if the airspace class wouldn't normally require ATC to do this for VFR traffic. This is typically used to get planes into or out of an airport that is experiencing localized worsening weather, without those pilots having to declare an emergency to override the controller's lack of clearance (normally if the airport is experiencing IMC it is illegal for a controller to clear a VFR flight for landing or even entry, as it's illegal for the aircraft to operate under VFR in such conditions).
VFR-On-Top - This is a special case of IFR which requires the same instrument training and certification, but allows a more VFR-like flight experience for the pilot. The pilot will be granted a "slice" of airspace by ATC, either altitude-only along his flight path or in three dimensions, within which the pilot has the freedom to choose his own altitude (typically to avoid clouds). The pilot gains primary responsibility to maintain minimum distances from other aircraft and from clouds within this airspace as he would under VFR.

As defined by ICAO, the classes are:

Class A - All flights must operate using IFR; no VFR or SVFR flight is allowed and VFR-On-Top is typically not granted due to the high activity level. Planes entering Class A airspace or making any self-directed change in flight path require ATC clearance. ATC provides full separation services, providing instructions to aircraft regarding required heading and altitude to keep aircraft on-course and well-spaced.
Class B - Flights can use all four flight rulesets, however all aircraft must be in contact with ATC and receive explicit clearance for entry or flight path deviation. ATC provides full separation services to all aircraft as well as directional guidance to IFR and SVFR.
Class C - Flights can use any of the four flight rulesets. Aircraft must be in contact with ATC and (except in certain countries including the U.S.) require explicit ATC clearance. ATC provides IFR guidance and separation of IFR and SVFR craft from each other and from VFR craft, while VFR craft receive "traffic advisories" but must maintain their own separation from each other.
Class D - Flights can use all four rulesets. Aircraft must be in contact with ATC and (except in certain countries including the U.S.) must receive explicit clearance for entry. ATC provides separation of IFR and SVFR flights from each other and provides traffic advisories to these craft of nearby VFR planes; VFR traffic may receive traffic advisories but is responsible for their own separation from all other aircraft.
Class E - Flights can use IFR, VOT or VFR; SVFR is allowed only when the airspace is established around a towered airport. IFR and SVFR flights are separated by ATC and require ATC communication and clearance prior to entry if the airspace is established around an airport; VFR aircraft do not require clearance or ATC communication, and do not receive separation services (though they may receive traffic advisories, ATC workload permitting).
Class F - Flights can use IFR, VOT or VFR but not SVFR. No clearance is required and ATC communication is only required for IFR. ATC provides separation between IFR flights and traffic advisories based on ability and workload, but separation is not guaranteed and IFR flights gain responsibility to "see and avoid". VFR flights may receive traffic advisories from ATC on a workload-permitting basis.
Class G - Flights may use IFR, VOT or VFR but not SVFR. No clearance is required and communication is only required for IFR. ATC has no authority or responsibility within this airspace; it provides traffic advisories as it is able prioritizing IFR flights.

In the United States, the classes are used as follows:

A - Airliner cruising altitudes, beginning at about 18,000 feet up to 60,000 feet within U.S. territorial boundaries and additional monitored airspace in international waters.
B - Surrounds large national and international hub airports in a big "inverted wedding cake" shape beginning at the surface 10 miles out and proceeding upward in wider layers to 10,000-12,000 feet at 20-30 miles out (the exact shape and number of layers depends on the specific needs of the airport and surrounding airfields or terrain); examples include Chicago O'Hare (ORD), Hartsfield-Jackson Atlanta (ATL), the Dallas-Fort Worth area (DFW/DAL), Boston Logan (BOS), the Washington, DC area (IAD/DCA/BWI), Los Angeles (LAX), San Francisco (SFO), Denver (DEN), the Houston area (IAH/HOU) and a few others.
C - Surrounds any airport that isn't Class B or within the footprint of one, but has significant scheduled service from national airlines (basically if it sees regular service from a 737 or larger it's at least Class C). Airspace shape is a smaller "inverted birthday cake" with an inner cylinder at the surface to 2,000 feet 5 miles in radius, and an upper cylinder from 2,000' to 4,000' feet at 10 miles out, with tweaks as necessary to accommodate the airport's specific needs.
D - Surrounds any airport that isn't class B or C but has a tower and instrument approach services. Includes most U.S. airports with commercial service using smaller narrow-body jets and turboprops, as well as most military air bases (AFB/NAS/JRB). Airspace shape is typically a single cylinder 4 miles in radius extending to 2500 feet; small variations are allowed.
E - Any airspace underneath Class A that isn't B, C, or D but can still be controlled by ATC. Typically starts at 1,200 feet above ground and extends upward to class A; a lower 700' "floor" is established 5 to 10 miles outside and underneath the airspace near most towered airports, with airstrips that do not have their own tower but do have instrument approach services also having a Class E "surface footprint" of 3 miles radius. This airspace is typically where ATC will grant "VFR-On-Top" clearance.
F - Not used in the U.S.; by FAA law, all "controlled" airspace requires ATC to guarantee IFR-IFR separation; any space in which it cannot do so is "uncontrolled" Class G.
G - Anything that isn't Class A-E. Typically airspace from the surface to 1,200 feet AGL, except where the Class E floor is lowered below 1,200'AGL, or any region above 1,200'AGL where radar or radio communications is disrupted by surrounding terrain.


text:
How do visiting foreign pilots access Duats or Duat?
I'm visiting the US and will get my foreign licence verified, but this means that I won't have a US license or medical. I understand that it is a requirement to sign up for Duats and Duat?!
Any idea or suggestion on how else to use it?

I've just arrived back home after being in the US for some months. I was required to have a FAA class 3 medical, because I did some flight training there, and luckily the one I've received is also is a student pilot certificate with the number on it you require to register for DUAT. Some of my colleges didn't have this number and so they were not able to register until getting there FAA pilot certificate. This will be send to your home adress, most probably when you are home again. In the US you'll only get a temporary certificate (peace of paper). The only number you'll find on it is your current license number.
Now what you can try: One of my colleges simply wrote an e-mail to duats helpdesk where he described his situation, giving all the information they require on their registration page with his foreign license number and attached a photography of his license and a proof that he'll be in the us for the next months. Less than 24 hours later he had a log-in. We had a student Visa, but if you don't have something like this, just try it without it, or take a photography of something else looking trustworthy.
Good luck and enjoy your trip!
Edit: I was just looking for the e-mail address, but for any reason my browser refuses to load duats website. As far as I remember, you'll find it at the registration page. If someonewho can access the website likes to add the e-mail adress please feel free to do so, I would appreciate your help.

Thanks. I emailed DUATS my CASA licence and the letter I have received from the FAA. They got back to me and just need a US address and a US phone number. Will update the post if I get access.

Falk is correct; you can contact the service providers directly, explain your situation and they should be able to provision an account without a US pilot's license or medical certificate.
DTC DUAT (duat.com) can be reached anytime at: 800-243-3828
CSC DUATS (duats.com) can be reached anytime at: 800-345-3828
As an alternative, may I recommend trying Lockheed Martin Flight Services' Pilot Portal at https://www.lmfsweb.afss.com.  They are the flight services contract provider for the FAA.  You can create an account by simply providing a valid email address.
It provides all of the same functionality as DUAT/DUATS, but Lockheed's briefing products are the exact same ones their telephone briefers use. Their website has a tool called "NextGen Briefing" that translates all of your briefing data into plain text, which makes reading your brief super fast and easy.  Of course, you can also read the coded text, if you're into that kind of thing (or you're training).
On the website, you can also create a pilot profile that is linked to your mobile number so when you call 800-WX-BRIEF to file a flight plan, their computers will prefill your aircraft data for you.
You can also file, ACTIVATE and CLOSE flight plans through the website.  Also, unlike DUAT(S), flight plans are immediately available to ATC/Flight Service when filed.


text:
What is the thickness of an A320 radome?
What is the thickness of an A320 radome? This is needed to run some simulations.

Nomex core material comes in thicknesses from 1/8" to 1".  A radome is probably around 1/2" or maybe 3/4" but you'd need an engineering drawing. Suggest you write to Airbus customer support.

It varies in different part numbers. Yes, Airbus offers a few designs to use. I'm not a structure expert, but I'm pretty sure the main difference is on their material, like Kevlar or Quartz, and how these material distribute (be reminded it's a composite structure).
From a maintenance manual of a few A320 radome designs, the overall thickness on the front face (yes, different area have different thickness) varies from around 7.5 mm to around 9 mm.
Hopefully that helps. And sorry that the exact could not be provided due to the manual is confidential and proprietary.
I'm not sure what kind of simulation you doing, FEA? CFD? Or just flight simulation? If you really want some exact numbers, try ask an airline or Airbus formally for their support.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
What is the correct traffic pattern at a towered airport?
When flying into a towered airport in VFR, is the pilot expected to enter a standard traffic pattern, or should the plane be flown in the most direct route to final as practical?
For example, if westbound into a class D airport with a north-south runway landing on runway 18, should the pilot enter the pattern at a 45 midfield, fly parallel on downwind as usual, then start the descent normally when abeam the threshold, turning left base and final? Or should the pilot simply fly to the north of the field and start the descent and turn a left final approach?
The AIM 4-3-13 doesn't really explain towered airport operations, as far as how to enter the pattern. This is the most relevant explanation I can find:

When necessary, the tower controller will issue clearances or other
  information for aircraft to generally follow the desired flight path
  (traffic patterns) when flying in Class B, Class C, and Class D
  surface areas and the proper taxi routes when operating on the ground.
  If not otherwise authorized or directed by the tower, pilots of
  fixed-wing aircraft approaching to land must circle the airport to the
  left. However, in all instances, an appropriate clearance must be
  received from the tower before landing.

I've only flown into a few class D airports (only 3 months since I got my license), and wasn't sure about how to approach the field in certain situations. Some were straight in approaches, but a couple were generally as I described above. The tower usually says to report at 3 miles, or when turning to final. "When necessary" ATC will issue clearances for traffic patterns, but what to do if they just tell you are clear to land? Does "circle the airport to the left" mean do the full pattern procedure?
During flight training I never experienced anything other than pretty much a straight in approach to class D.
Edit: I found this explanation on a flight instruction website: "Pilots do not fly a standard traffic pattern at a towered airport, with a 45-degree entry to the downwind leg. Instead, aircraft enter the airport vicinity as instructed by ATC, reporting arrival on an assigned pattern leg and then accepting further instructions or a clearance to land."
This seems to contradict the AIM explanation. And again, what if ATC doesn't instruct anything, what are they expecting the pilot to do? A standard pattern or a straight in approach as direct as possible?

The correct traffic pattern at a towered airport is the one the controller instructs you to fly -- If there's any ambiguity or you're not sure what they want you to do key the mic and ask them to clarify.

But what if they don't instruct you to fly any pattern? What is ATC expecting me to do in the above situation? I could fly to the north of the field, do a left turn to final and in essence be "circling to the left".

Not a full answer, but if I was given that instruction I would think to myself "hmm, that isn't standard ATC phraseology per the pilot-controller glossary, so I had better ask him what he means....".

When flying into a towered airport, you will be given specific instructions, as per the ATC Handbook, Section 10, Arrival Procedures and Separation such as:

"make left traffic for runway 15"
"enter a right base for runway 15"
"make straight-in runway 15"

You can also request whatever you want, like: "Tower, Cessna 3-3-Lima, information bravo, requesting left base for 15"," and the controller will then evaluate your request and issue you instructions.
These instructions refer to the following diagram form the Pilots Handbook of Aeronautical Knowledge (PHAK, p. 13-12):

Traffic patterns are also covered in the Pilots Flying Handbook, Chapter 7, and states that:

When operating at an airport with an operating control tower, the
  pilot receives, by radio, a clearance to approach or depart, as well
  as pertinent information about the traffic pattern.

Which type of traffic pattern information ATC might give you, depends such factors as where you are relative to the airport, other traffic, noise abatement, obstructions, local procedure, etc.  For example, in the diagram below:

N or NE of the airport, you could be given "Left traffic"
NW you could be given a base entry
W you could be given a straight in.
If you're SW, S, or SE of the airport, you could be given the same pattern instructions as the north side, but with RIGHT instead of LEFT, or you could be instructed to overfly the field and enter, say, left downwind.

If you are in contact with ATC, and don't know what you're expected to do, then key the mic and ask the controller.

If ATC instructs to "enter a right base for runway 15", does that mean fly directly to the base leg and not enter a standard right pattern by joining the downwind? What about "make left traffic for runway 15"? Does that mean enter the downwind leg? If I were instructed to do that, I would probably ask what ATC means by "make left traffic".

Traffic patterns earns an entire chapter in the PHAK: http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2013.pdf

@rbp It's worth noting that the section on traffic patterns begins with "At those airports without an operating control tower". Not that you can't use these procedures to get onto a downwind leg if the tower instructs you to to enter a downwind, but it's better to ask than to be the guy maneuvering to enter on a 45 when the tower expected you to enter on a base leg.

@voretaq7 -- read the whole sentence: "At those airports without an operating control tower, a
segmented circle visual indicator system [Figure 13-13], if
installed, is designed to provide traffic pattern information. " (emphasis mine).

Also, I added some additional explanations, with references, which should clear up any confusion.

@eric A somewhat related question, especially some of the comments on the answer: http://aviation.stackexchange.com/q/1840/69

@rbp, The traffic pattern diagram is helpful but the ATC Handbook doesn't

@rbp, the editor timed out on me.  The ATC Handbook implies there are two ways to fly to the final approach. 1)Specific instuctions as listed below 2) standard pattern to the left.  "Specific traffic pattern information (may be omitted if the aircraft is to circle the airport to the left).
PHRASEOLOGY-
ENTER LEFT/RIGHT BASE.
STRAIGHT-IN.
MAKE STRAIGHT-IN.
STRAIGHT-IN APPROVED.
RIGHT TRAFFIC.
MAKE RIGHT TRAFFIC.
RIGHT TRAFFIC APPROVED.
CONTINUE. "    This page doesn't explain what these specific instructions mean. "MAKE" seems to be a keyword with a special meaning.

@eric I think we are getting out of the realm of information and into the realm of ground instruction. I think you need to spend some time with the CFI who signed you off for your private pilot's checkride, specifically on PTS III(b)(1): "Exhibits satisfactory knowledge of the elements related to
traffic patterns. This shall include procedures at airports
with and without operating control towers." I also added another reference on traffic patterns in the Pilots Flying Handbook.

@rbp, I already understand traffic patterns. If my CFI needs to explain to me what pattern a towered airport expects me to use without giving me direct instructions, then why can't anybody here explain it to my satisfaction? Once again, I UNDERSTAND TRAFFIC PATTERNS! Please re-read my question, it isn't about what do if they give me instructions. My question is what do they expect me to fly if they DON'T give specific instructions. You answered my question assuming ATC gave instructions.

The reason you haven't gotten an answer to your question is because you're asking about something that doesn't happen, except when the controller doesn't follow ATC procedures. When you contact a towered airport, you will be given a clearance as to what kind of approach to make. If you don't get a clearance, the proper response is to key the mic and ask the controller what he wants you to do. See the quote from the PFH in the last edit.

(This is more from EASA regs, but FAA's should be identical)
Flying into class D airspace as VFR you are completely responsible for traffic separation. ATC will give you traffic information about other VFR and IFR flights, and traffic avoidance on request.
You need to be able to see other traffic and separate just as you would in uncontrolled airspace.
This tells me that , unless otherwise instructed  , I need to fly as usual and enter an appropriate traffic pattern to give me ( and others ) the chance to maintain visual separation.

When are you not responsible for traffic separation under VFR? Even under IFR, you're responsible to see and avoid in VMC

In Class C ATC will provide separation vs IFR flights. In class B ATC will separate against all traffic. Of course you are still responsible to look out the window, but in Class D you DON'T GET ANY traffic separation service, just information (hence the wording "completely responsible" . Can I get my downvote back now?).

Those are separation SERVICES, which is a shared responsibility between ATC and the pilot; the pilot is still response to see and avoid. Under IMC, ATC is fully responsible.

I'm guessing the down vote is because it doesn't answer the question about what pattern to fly.

This might be my cold medicine acting up, but just how is my post not answering?  Q: "standard pattern or direct approach in class D when not instructed by tower?" A:"need to fly as usual and enter an appropriate traffic pattern ". What am I missing?

and just for fun facts: Pilots could still be held responsible for loss of separation in IMC aswell.

maybe it would help if you defined or cited a definition for "as usual" and "appropriate"?

Let us continue this discussion in chat.


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Structural design software for airplanes
What are the main structural design software packages that are used by the most of the aircraft manufacturers. There are a number of software packages but which one is widely accepted and used for the structural design of the aeroplane.

Welcome to [aviation.se]. Currently, your question might not be suitable, as it's asking for recommendations mainly based on opinion. Plus, it could change at any time, depending on the situation. These types of questions are quite difficult to fit into the Stack Exchange network, as explained in our [About] page.

I actually really like this question, but I agree with @Qantas94Heavy.

Maybe we could try to create a CW listing and describing the main ones and try to match them to the companies as far as we know...

CATIA has been used in large projects like Boeing 777 and companies like Lockheed Martin.
I wouldn't say it is the standard across the aerospace industry though as other software like Pro E and Solidworks can be used as well.

CATIA is primarily a CAD software for 3D design (which is used in aerospace). Some tools for meshing and FE-analysis have beend added over time, but for major structural work dedicated FE packages are used.

@yankeekilo I completely agree. I was focusing more on just the design aspect instead of the FE analysis (I was under the assumption that the OP was looking for just design). However just like any software used in the process of engineering the goal is to know the fundamentals of design, simulation and analysis so that you can apply it to any software suite provided to you.

There are many package available for structural analysis, but I know that NASTRAN/PATRAN are used extensively in aerospace engineering.
The software was originally developed for NASA in the sixties and has been expanded with a suite of problem solvers for various structural problems including fatigue and acoustics.


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Where can I find records of old FAA registrations?
I know where to find details for FAA N-Number registrations. But where can I find records and details on older FAA NC, NR, NL, and NX numbers?

Its entirely possible that they aren't available electronically. Those prefixes were used prior to 1949 and may not have been digitized. You can probably try to request copies of those records through the FAA, but I'm sure it won't be easy, or cheap.

Resource location is off-topic as defined by the help center.

NC, NR, NL or NX are not necessarily older aircraft. Any aircraft more than 30 years old can use NC instead of just N.
So, to find the a/c registration you just take out the C.
I own a glider that was built in 1965 so my numbers are NC and 5 digits.
It should be the same for R, L, and X, which are any aircraft that has a restricted, limited or experimental airworthiness certificate can use those letters after the N. See FAR Part 45.22.

This does not answer my question on where I can find info on these registrations

The point is that the premise of your question is incorrect. Only NC is for 30 yrs or older aircraft. For all of those registration marks, remove the C, R, L and X and search on that on the FAA web site.


text:
Why was the Boeing SST numbered "2707"?
Boeing worked its Supersonic Transport (Boeing SST 2707) design in the 1960s. They gave it the number "2707". Why was this aircraft given that number? Did it have some significant inside-Boeing relation to the B707 or was it just some number that followed another Boeing numbering scheme?

Its internal model number 733 but not 2707. The name may be a mixture of Lockhead L-2000 and B707

For those voting to close, I don't see how this could be primarily opinion based. There should be a concrete reason, however hard to discover. The only opinion based answers will be those choosing to speculate.

The planned cruise speed was Mach 2.7 so I always assumed 2707 was a combination of Mach 2.7 and the then current Boeing 707.

But the SST had nothing at all to do with the 707, and the 707 had been in production for eight or nine years by 1966, when the "2707" designation was first used to refer to the SST. By that time, the 727 was in service, the 737 was in production and the 747 project had begun.


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Why does landing gear extend backwards and retract forwards?
As you can see in the below image the front landing gear is retracting forwards, meaning that it extends forwards. What is the reason why they are made to drop backwards instead of forwards?

Image Source

It doesn't always, but this is often done so that the air helps to push the gear down (back).  This is useful in situations where the normal means of extension fail.

@fooot Thanks, I had a feeling that the question was already asked somewhere here but I could not find it.

There are quite a number of retractables where the main gear retracts inwards, towards the fuselage.  I don't have specific numbers, but I think it's the most common pattern on light planes, at least.

@jamesqf I know about that. The main gear on the plane in this image had that too. I am just asking about why backwards and not forwards for the gear that does that.

@SMSvonderTann: Then perhaps you should re-word your title & question to make it specific to nose gear?


text:
Why are number of landings logged?
I have flight logs for a WW II B-24 navigator who flew with a combat crew in China Burma India.  There is a column for number of landings.  The entries range from 1 to 5 or 6, mostly 1 or 2.  The time can be as long as 8:00 to 10:00 or more.  Why is the number of landings recorded?  Is that still done today?

When you say flight logs, do you mean logs for the navigator or for the aircraft?

Yes, it's still done today, at least in military aviation.
It's to ensure that the undercarriage does not excede the number of landings it has to endure before being checked/overhauled/replaced. Landing an aircraft can typically be the most stressful regime of flight in terms of loading of certain bits of the aircraft, so it is pertinent to log how many times it happens per flight.

how many times it happens per flight you mean that a touch-and-go would be/is counted as "landing"?

That's correct.

@LiamBaron is this aircraft logs, or pilot logs? As a GA pilot I've always logged landings for my own FAA records, but never for an airframe or in an aircraft flight log.

My answer is for aircraft logs. In military this record is always kept as part of the aircraft documentation.

though the  question seems related to the logs of a crew member, not of the aircraft.

I'm not sure if this is specifically a military question or a general question. In general aviation (FAA) you are required to do a certain number of landings every 3 months to stay current. So landings are logged for this reason.
The specific regulation is 14 CFR 61.57 (a) (1), which says (emphasis added):

[…] no person may act as a pilot in command of an aircraft carrying
  passengers or of an aircraft certificated for more than one pilot
  flight crewmember unless that person has made at least three
  takeoffs and three landings within the preceding 90 days […]

I am not yet rated for IFR, so I'm not sure on the specifics about IFR currency mentioned in this regulation. The currency for VFR related flight differs from day and night; however, 3 night landings in 90 days will count to keep you current, while 3 day landings will only keep you current for daytime VFR.
A note on military training:
I was able to find this book/article that alludes to the training of navigators during the second world war; on P.585:

Before 1933 instruction in navigation was given only as part of pilot training.

If the individual in question had a military career and joined before '33 he may have been a pilot first and simply continued with the same log book. Why the landings were logged may just be force of habit. Either way its an interesting read on how difficult it was to be a navigator at the time and exactly what it took to become one.

Pilot logbooks also have a column for number of landings as well. (At least they did when I was flying)

They still do, at least the Jeppesen one I use has it, I believe it is there for this very reason.

@dave if i read correctly it is logbook for navigator, not the pilot. Is there any info regarding navigator logbook as well?

I can not find anything specific but the navigator certification/position is not really issued or filled anymore and thus there is not really a need for navigator specific log books. That being said there may have been specific log books for them back in the day and the navigator certification may have also had a landing requirement but I do not know so I cant comment on it as it is not really addressed in the FAR currently.

Landing is not the easiest thing on an airframe! It imparts a lot of stress, and everything we build is designed and evaluated by some statistician to endure a certain number of uses + or - some standard deviation that he/she defines. Even the keys on your keyboard are meant to endure a certain number of presses.
Additionally, if you CAN collect data that you suspect may be useful later, why not? You never know when you may want to use it for something you didn't intend to.
Not sure about the navigator though.

It would also track take-offs, of course (+/- 1) which I guess are also stressful.

For aircrew, yes there are certain requirements including no. of LDGs to be conducted within xx timeframe (typically 3 months / 90 days) in order to maintain currency. This information is recorded in the Pilot Logbook. Mine didn't have a special column (NZCAA type) so you would just write what was pertinent in the narrative, using as many lines as required.
For part 91 & 135 GA aircraft I'm not aware of any that require records to be kept of LDGs. In the airline industry cycles are recorded - this pertains more to the number of pressurisations, but on some a/c I believe LDGs are recorded also.
On the McDonnel-Douglas A-4K Skyhawks (Scooter in USN) that I maintained in the '80s we recorded LDG cycles, as well as g-force excursions. This pertains to airframe fatigue and cycle life. During peacetime fighters often last many more years (decades?) than would be reasonable for designers to estimate under true combat conditions, hence airframes can actually wear out, by reaching design time/life limits. This is especially applicable to naval aircraft operating from carriers. Even when the RNZAF operated A-4s, land based only, the initial  "thump" of LDG usually produced more g, albeit momentarily, than a maximum performance ACM manoeuvre. They could have been landed "softly"; main RWY at their home field was ~2500m, but what the heck these were carrier aeroplanes and the pilots knew it. So they took delight in extending that 500mm or so of impact absorbing oil-damped undercarriage travel (top MX bikes have only 300mm) to its full effect. That was a good reason to log landings.
JSB

I suspect it has to do with the fact that pilots want/need records of that for certification purposes and Pilot In Command can  change in the middle of a flight. Seems silly for a navigator though.

Landing is one of the more important times where navigation is needed.

@fooot Finding the airport and landing there are entirely different skills.

All the answers to date seem to have missed the most obvious part: landing the plane is by far the most difficult (and arguably the most important) part of flying, at least VFR.  So the reason a certain number of landings within a given period is required to maintain currency is simply to ensure that the pilot remains practiced in doing them.  And the reason they're logged (and logbooks have a column for it) is so that you can show currency if you ever need to.
While landings might need to be recorded for some military or commercial airframes, it's simply not true for most aircraft.


text:
Why is an unpressurized takeoff performed?
Why would an aircraft perform an unpressurized takeoff? What conditions lead to this being beneficial?

related: Why do pilots disable the air-conditioning 'packs' during takeoff?

Typically, the pressurization system is run by engine bleed air. Using that bleed air means you have less engine power available than is maximally available with the bleeds off. If you're on a runway that requires all your power, you do a no-bleeds takeoff, which means you have no pressurization. Shortly after takeoff you would turn the bleeds on.

In many cases, the APU can be used at lower altitudes to provide pressurization when engine bleeds are off for takeoff.  That's normal, but if the APU is inop and performance requirements drive a bleeds-off takeoff, then unpressurized is the only option.

In the EMB-145 if we needed A/ice on for takeoff we did it unpressurized.  Engine bleeds on, a/ice on, packs off.

@RalphJ: Well, you don't really need pressurization during take-off. The pressure inside is not higher than outside up to ~7000 ft and there are few airports higher than that.

@JanHudec Departing from a sea level airport, climbing through 7000' the cabin is typically about 1000' - 2000' -- the cabin climbs slowly from SL to 8k during the same time the aircraft climbs from SL to cruise at 35-41k. With an unpressurized takeoff, passengers' ears feel the initial 2000+ FPM climb, instead of a more gentle 300 FPM (normal) cabin rate of climb.

Packs off doesn't mean that the cabin is unpressurized. The outflow valve(s) are closed and the cabin pressure remains steady at aerodrome level.
This will give better engine thrust as mentioned above.
Unpressurized cabin would mean outflow valve in open position and cabin pressure would be equal to ambient pressure. This is not allowed on commercial flights (at least JAA/EASA regulations).
I flew one ferry flight unpressurized and almost popped my ears on takeoff because of the high climb rate.

Turning off both packs in flight WILL depressurize the cabin, closed outflow valve notwithstanding! If the cabin is really tight you might be able to least reduce the cabin rate of climb taking off with packs off, but the term "unpressurized takeoff" would still apply, since you are, temporarily at least, without any means of pressurizing it.  Can't speak to JAA/EASA, but in the US an unpressurized takeoff is considered an entirely separate creature from an unpressurized flight.  At my carrier, we can do the former, but not the latter (with passengers).

@RalphJ That's correct. The cabin is not a closed bottle, it will always leak a bit. There's still a significant difference between packs off take-off and an unpressurized take-off. With packs off and pressurization on (since automation will drive the outflow valve(s)) you'll end up with around 300-700fpm cabin rate. Unpressurized (outflow valve open, or a door, would be equal effect) take-off will give cabin rate equal to aircraft climb rate at take-off, which would be anywhere between 1000 and 3500 fpm.

@RalphJ As a conclusion, I would say that the term "Unpressurized take-off" may apply procedure-wise, but I still wouldn't consider the aircraft unpressurized. The cabin is pressurized whenever there's a difference between cabin pressure and ambient pressure.

One reason for an unpressurised takeoff would be if the aircraft's pressure hull is damaged, and it's making an unpressurised ferry flight to somewhere it can get repairs.


text:
What's the reason for "pre-pressurization" of the cabin prior to liftoff?
I'm reading a Citation M2's Pilot Training Manual, and it says:

...When the throttles are advanced for takeoff, the bleed air turns on
  (if not already on for heating), and the pressurization controller
  starts closing the outflow valves to pressurize the airplane. The
  cabin altitude may descend by as much as 200 feet during this
  pre-pressutization prior to lift off.

What's the purpose of the pre-pressurization prior to lift off?

https://aviation.stackexchange.com/questions/16796/why-is-cabin-pressure-increased-above-ambient-pressure-on-the-ground


text:
Is baggage always offloaded when a passenger does not travel?
For terrorism concerns I think many airlines offload checked in baggage if a passenger somehow does not end up travelling on a flight.
How strictly are these rules followed? e.g. If a connecting passenger with a tight connection cannot make it to the gate in time will the airline actually send in a ramp guy into the baggage hold to remove specific pieces of baggage? How feasible is it to do thing when the bags are in pods or the Unit Load Devices? Do they have to remove the load device from the hold before they can extract a specific bag?
How does the gate delay of just waiting for the errant, late passenger compare to the time & effort needed to find & offload his bags?
PS. Since bags do get misrouted I'm sure at least some bags fly without a passenger owning them on board.

I'm voting to close this question as there are too many sub-questions contained. You may wish to narrow the scope.

The sub-questions are all facets of the same issue. They aren't unrelated. In a way, the questions only serve to clarify the question.

"How strictly are these rules followed?": Suppose they are not, do you want anybody to know it?

I'm voting to close this question as off-topic because this question cannot be answered, for obvious security reasons.

AFAIK the rules that prevent baggage to be loaded if the owner is not on the flight only apply to persons on a watch list. Their luggage is set aside until they board. That happened with some of the 9/11 hijackers and is probably why Mohammed Atta's bags were left behind. It would be way too difficult to do this with every passenger on every flight.

@TomMcW: You should say that it's for the US, EU uses other rules: "5.3.3.2 Hold baggage that becomes unaccompanied baggage due to factors other than those mentioned in point 5.3.2 shall be removed from the aircraft and rescreened before loading it again."

@mins Don't you hate having to keep reminding us Americans that the rest of the world exists. :)

@TomMcW I think the rules on that have changed in the U.S. since 9/11, too. As far as I know, it's still not completely guaranteed that your bags won't fly without you, but it's less likely now.

By the way, there's already some information about this topic on travel.SE: Would I delay flights, when not showing up for part of the journey?

I'm voting to close this question as off-topic because I feel it belongs to travel.SE

My luggage was unloaded of the plane when I missed my connecting flight in Mosocow (didn't showed up in time at the gate).
The route was CDG=>SVO=>ULN So yes, baggages ARE offloaded.

Normally, baggage takes much longer to switch flights than self-loading cargo, so your scenario is highly unlikely.
In the event of a passenger missing and his/her baggage already on board, all bags need to be unloaded until the orphaned bag is found. When ULDs are used, those must be unloaded first and are then unpacked, mostly on the apron next to the aircraft.
Waiting for the missing passenger is an open-ended game. At some point, you must decide on a course of action with a fixed exit so you can move on.
Normally, every airline is required to unload an orphaned bag. I am sure some are more strict about this than others.

Thanks Peter! I guess if they were very very strict we'd never have lost bags, eh? :)

Is there a faster method to identify and pull out an orphaned bag


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What is the optimal sequence of departures and arrivals on a single runway?
When in a peak load scenario with plenty of departing & arriving aircraft to keep the ATC pipeline full, are there considerations that make a certain sequence of Departures / Arrivals that optimizes throughput?
For specificity, let us assume a single runway in use and no general aviation aircraft with predominantly jet traffic and multiple runway entry & exit taxiways available. Including high speed exit turnoffs.
I typically see a sequence something like:
 Dep-Dep-Arr-Dep-Dep-Arr

But an alternative optimum might turn out to be:
Dep-Arr-Dep-Arr-Dep-Arr

etc.
I realize that the specifics will depend on the exact aircraft etc. but just to use an idealized model what would result from typical operating constraints. e.g. You need to allow a certain separation during approach but you can have multiple aircraft lined up for take off. So is the potential to squeeze departures into the "holes" higher? Also, you can clear a second departure after a first far more rapidly, than the landing-to-landing interval right?
Just wondering, if you had to set up a formal optimization model what sort of parameters & constraints should go into the model as inputs.
A follow up question: Say you had two runways available in parallel & widely spaced apart. Does it make sense (for throughput) to dedicate one to landings & another to takeoffs or is it more efficient to mix landings & takeoffs on both runways?
R18L: Dep-Dep-Dep-Dep-Dep-Dep-Dep-Dep-Dep
R18R: Arr-Arr-Arr-Arr-Arr-Arr-Arr-Arr-Arr

vs
R18L: Dep-Dep-Arr-Dep-Dep-Arr-Dep-Dep-Arr
R18R: Dep-Dep-Arr-Dep-Dep-Arr-Dep-Dep-Arr

PS. If further simplifying assumptions are necessary, let's imagine a hypothetical airport serving a single aircraft type, say A320 only. Or assume any type you will to be representative of a wide class of aircraft just to get the modelling started.

Interesting question. Not answers, just elements of the problem: Airport Operations --- Airport Runway Optimization --- Models for Aircraft Landing
Optimization

This is a pretty broad question that's going to be dependent on a lot of factors. Some airports will have more departures at one time of the day and more arrivals at another. In your first example there are twice as many departures as arrivals whereas in your second they are even. Most airports with multiple runways use separate arrival and departure runways

@TomMcW Another way to ask is: If as an airport I have a certain number of arrivals & departures to handle, as an ATC is it easier if they came segregated or mixed?

@mins Nice links. One of them talks about "optimal departure sequence". That's sort of close to that I am asking. My question is about an optimal departure+arrival sequence.

There's a ton of info about this subject on the web. Everybody from the FAA, to airport management, to universities to private consulting firms have visited this subject. And every bit of it is published on the web. Just about every major airport has some kind of traffic study available. There's so much I don't even know where to start to summarize it into an answer. It's clear that arrivals and departures are done on separate runways whenever possible. There isn't a whole lot of info on what to do on a single runway. There aren't a whole lot of real busy airports with only one runway. Maybe i

...maybe if you can come up with a busy single-runway airport they will have a traffic study that will answer that question.

@TomMcW But a lot of what people think as "conventional" wisdom seems wrong. e.g. Take the point you mentioned: "arrivals and departures done on separate runways where possible" That seems the non-optimal way to do it, at least from a throughput viewpoint. Mixing arrivals & departures seems to give a higher throughput. According to the LHR report mixed mode gives 96 movements an hour. Whereas separate runways for arrivals vs departures only gets you 84 movements.

@TomMcW In any case, I'm not disputing that there's a lot of info on this topic out there. Just that having a SE-Aviation summary distills this info into a enduring, summary.

It seems to me, from a wake vortex pov that you'd want to alternate dep and arr. Not sure what the reason is for separating them.

Possible duplicate of http://aviation.stackexchange.com/q/3715/558

Try looking at NATS Gatwick Arrivals Review for information about the 900 flights a day on a single runway.  You should also look at time based separation currently trialling at Heathrow and expected to be deployed at Gatwick

Usually a mixed usage runway is more efficient than a dedicated arrival runway(s). Arrivals are harder to get closer together than departures as well. Running a final with 5 mile gaps(for wake and all departures) is a good way to do dep-arr-dep-arr.
With dedicated Dep-Arr runways, and assuming you have aircraft ready to go, your expected hourly rate for Arrival only runways is usually around 30, whereas with a departure only runway the rate is about 45 or so(assuming minimal spacing, and have decent fan headings, and the departure routes are split decently to allow good separation heading to the center).